1. Field of the Invention
The present invention relates to a starter for starting an engine mounted on vehicles such as passenger cars, and more particularly to a pinion shift-type starter for vehicles having idle-stop apparatus.
2. Description of the Related Art
An increase in vehicles including an idle-stop apparatus that automatically controls stop and restart of an engine (referred to, hereinafter, as idle-stop vehicles) is expected in the next few years to reduce carbon dioxide emission and improve fuel efficiency.
An idle-stop vehicle frequently encounters situations on the road in which the engine is automatically stopped, such as stopping at a traffic light at an intersection, and temporarily stopping during a traffic jam and the like. Therefore, the engine is required to be restarted as quickly as possible and with reliably when a driver performs an operation to move the vehicle (such as a release operation of the brake pedal, or a shift operation to a drive range) after the engine is stopped.
Japanese Patent Laid-open Publication No. 2008-163818 discloses a starter. In the starter, after an engine is completely stopped, a coil of an electromagnetic switch is energized, and a pinion gear is meshed with a ring gear of the engine. The state in which the pinion gear is meshed with the ring gear is subsequently maintained even when energization of the coil is stopped, as a result of movement resistance generated when the clutch moves integrally with the pinion gear along an output shaft. In the starter, the meshed state between the pinion gear and the ring gear can be maintained in while the engine is stopped. Therefore, the engine can be restarted in a short amount of time in response to an engine restart request.
However, in the document No. 2008-163818, because the pinion gear is meshed with the ring gear after the engine has completely stopped, the engine cannot be restarted immediately after it is stopped. In other words, the coil of the electromagnetic switch is energized and the pinion gear is meshed with the ring gear after a judgment is made that the engine has completely stopped. Therefore, time is required until the pinion gear actually meshes with the ring gear after the engine is completely stopped. In other words, the pinion gear has not yet meshed with the ring gear at the time the judgment is made that the engine has completely stopped. Therefore, the engine can not necessarily restart quickly.
Moreover, the patent document described above, states that the pinion gear can be meshed with the ring gear during inertial rotation that occurs until the engine comes to a complete stop. In this instance, because the ring gear is rotating at a low speed, the pinion gear can be meshed with the ring gear merely by being pushed toward the ring gear side, without a motor being rotated. Considering the idle-stop vehicles, starters are frequently used to perform idle-stop compared to starters that do not perform the idle-stop. Therefore, wearing of a motor contact point may progress due to frequent use of the motor.
However, in the starter described in the patent document described above, a single electromagnetic switch serves to push the pinion gear toward the ring gear side via a shift lever, and to open and close the motor contact point. In this configuration, the motor contact point closes and a rotational force is generated in the motor almost simultaneously with an end surface of the pinion gear coming into contact with an end surface of the ring gear. Therefore, it is not possible to push only the pinion gear towards the ring gear and mesh the pinion gear with the ring gear, without rotating the motor.